Antimatter consists of subatomic particles that are structurally identical to subatomic particles of matter, but have opposite fundamental properties. For example, positrons (antielectrons) possess the same quantum characteristics as electrons (spin, angular momentum, mass, etc.) but are positively charged. Antiprotons possess the same quantum characteristics as protons, but are negatively charged. When an antiparticle, such as an antiproton, collides with its corresponding matter particle (in this case a proton) they annihilate each other, converting their mass into energy. Antimatter annihilates so readily that it only exists on earth when it is artificially generated in high-energy particle accelerators. Elaborate means have been developed for storing antimatter on earth once it has been created. Often these means have included large, fixed machines such as the low-energy antiproton ring (LEAR) at CERN, in Switzerland, or the Antiproton Accumulator at Fermilab in the United States. Devices such as LEAR are extraordinarily complex, and relatively expensive to build, maintain, and operate.
Apparatus and methods for the production, containment and manipulation of antimatter, on a commercial scale, are also known in the art. For example, U.S. Pat. No. 4,867,939, issued to Deutch on Sep. 1989, provides a process for producing antihydrogen which includes providing low-energy antiprotons and positronium (a bound electron-positron atomic system) within an interaction volume. Thermalized positrons are directed by electrostatic lenses to a positronium converter, positioned adjacent to a low-energy (less than 50 KeV) circulating antiproton beam confined within an ion trap. Collisions between antiprotons and ortho-positronium atoms generate antihydrogen, a stable antimatter species.
Deutch proposes use of an ion trap which can be either a high-vacuum penning trap or a radio frequency quadrupole (RFQ) trap, with a racetrack design RFQ trap being preferred. Deutch provides non-magnetic confinement of the antimatter species by use of dynamic radio frequency electric fields. Deutch does not disclose any method or apparatus for confining antiprotons in a manner appropriate for their storage and transportation to a location distant from their creation.
In U.S. Pat. No. 5,206,506, issued to Kirchner on Apr. 27, 1993, an ion processing unit is disclosed including a series of M perforated electrode sheets, driving electronics, and a central processing unit that allows formation, shaping and translation of multiple effective potential wells. Ions, trapped within a given effective potential well, can be isolated, transferred, cooled or heated, separated, and combined. Kirchner discloses the combination of many electrode sheets, each having N multiple perforations, to create any number of parallel ion processing channels. The ion processing unit provides an N by M, massively-parallel, ion processing system. Thus, Kirchner provides a variant of the well known non-magnetic radio frequency quadrupole ion trap that is often used for the identification and measurement of ion species. Kirchner's multiple electrode structures (FIGS. 1 and 2) appear to serve as an ion source and confinement barrier.
Kirchner suggests that his apparatus is well suited for storing antimatter. More particularly, Kirchner suggests that as antimatter is produced, groups of positronium or other charged antimatter can be introduced into each processing channel and held confined to an individually effective potential well. Kirchner also suggests that large amounts of antimatter could thereby be "clocked-in" just as an electronic buffer "clocks-in" a digital signal. It would appear that the adaptive fields created by Kirchner's device might allow for the long-term storage of antimatter in a kind of electrode sponge. However, in suggesting the application of his device to antimatter confinement, Kirchner fails to disclose many essential aspects of such a device. For one thing, he makes no mention of vacuum requirements, which are essential to long-term confinement, storage, and transportation of antimatter. For another thing, Kirchner fails to provide any effective means for introducing antimatter, e.g., antiprotons, into his device or for effectively removing them from his device once they have been "clocked" through.
Antimatter could have numerous beneficial commercial applications if it could be effectively stored and transported. For example, antiprotons may be usefully employed to detect impurities in manufactured materials, e.g., fan blades for turbines. Positrons (generated by radioisotopes of common elements) are used for medical imaging applications, e.g., Positron Emission Tomography (PET), which does not require the delivery of radiation as in conventional x-rays and cat scans. Additionally, concentrated beams of antiprotons may be directed onto diseased tissue, e.g., cancer cells, to deliver concentrated radiation to those cells thereby destroying them, but without significantly affecting surrounding healthy tissue.
Commercial and industrial applications of antiprotons have been hampered by the fact that such activities must be undertaken at, or very close to, the place where antiprotons are generated, e.g., a high energy physics laboratory operating a synchrotron or the like. This is due to the very short life expectancy of an antiproton. As a result, antiprotons are not often used in, e.g., medical applications in public and private hospitals, due to the extraordinary requirements associated with the operation of a synchrotron of the type used to generate antiprotons in significant quantities.
In particular, a need exists in the biomedical radioisotope arts for a transportable source of positron emitting isotopes with short half-lives for use in PET imaging procedures. For example, radioactive fluorine (positron emitter) is often produced in small synchrotrons that are located at central hospital complexes. In this procedure, a collection of nonradioactive fluorine atoms are bombarded with a stream of antiprotons emanating from the synchrotron ring. A number of antiprotons from the stream will interact with a corresponding number of fluorine atoms. During this interaction, an antiproton will knock one of the neutrons situated in the nucleus out of the fluorine atom. The reduction in the number of protons in the nucleus of the fluorine atom causes it to become radioactive, and eventually to emit a positron as a decay product. These radioactive isotopes of fluorine are then introduced into a patient's body where their decay is monitored.
The clinical operation, however, is difficult and expensive because of the 120 minute half-life of the isotope. The procedure could be made considerably less expensive, and more convenient, if the necessary short-lived isotopes could be produced in sufficient quantities at the patient's bedside using a portable source of antiprotons. The prior art does not disclose a container adapted for confining, storing, and transporting antiprotons that is capable of movement, via conventional terrestrial or airborne methods, to a location distant from their creation. Such a container would not only need to be capable of maintaining an effective population of antiprotons, at sufficient population levels, to provide adequate quantities for use in medical and industrial applications, it would also need to be small enough in size to be easily handled in a hospital environment, preferably including a patient's room. Also, such a container would need to be both capable of manufacture at a reasonable cost and reusable.